If you have the time, I would follow ACA's Great Parks from Misoula to Whitefish/Columbia Falls and pick up the Northern Tier there. If you have even more time, I would go east on the NT to Glacier National Park, spend a day riding up and back down the west side of Goint to Sun Road and then head back west on the NT. Once you get near Anacortes you can ride south to Seattle, which is, obviously, a major transportation hub.
The NT is different riding than thet TA west of Missoula. A lot of the OR mileage is through high desert. It can get crispy critter hot with little shade. You will have more forest on the NT, although it can get very hot east of the Cascades, too. The stretch between Winthrop, and Tonasket was very warm and arid even in early June.